In recent years optical character reading systems have been employed to read a presented character from a document and to supply a general purpose computer with encoded data representing the presented character. Typical of such optical character reading system is the system disclosed in the U.S. Pat. to Beall et al, 3,840,856, issued Oct. 8, 1974. The Beall et al patent discloses apparatus for scanning a presented character to derive an array of voltages, which array of voltages are quantized at three quantizing levels to form data field geometric configurations represented by binary signals. The information content of discrete areas of the data field geometric configurations is compared in a sequential manner with predetermined voltage characters. A favorable comparison results in the discrete area being characterized as one of the predetermined voltage characters.
One disadvantage of the technique employed in the Beall et al patent is that features of the patterns are interrogated in a discrete fashion with no regard for the inter-relationships between these discrete areas of the features based upon size, such as length, heighth, and width of the character.
Another method of pattern or character recognition is matrix recognition in which an entire pattern is stored in a matrix and compared against stored patterns. While such a method has a high degree of accuracy in interrogating distorted and partial pattens, such a system is very costly and complex pattern interrogation methods must be used.
The United States Pat. to Chow, No. 3,341,814, issued Sept. 12, 1967, which has the same assignee as the subject application, discloses an improved method for identifying alpha-numeric characters or other patterns by statistical decision techniques based on nearest neighbor dependence. The subject invention uses this broad concept of neighborhood dependent areas in a novel fashion to overcome any of the problems of the prior art system, especially in regard to the recognition of distorted and mutilated patterns.